Headlamps in automotive applications have increasingly become more sophisticated. For example, recently headlamps producing a continuously variable illumination range have become available. In this example the illumination range may be varied by one or both of changing the intensity of light and changing the direction of light emitted by the headlamps.
Varying headlamp illumination intensity can be accomplished in several different ways. One example is to provide a pulse width modulated (PWM) signal to the headlamp. By varying the duty cycle of headlamp power, the headlamp illumination intensity can be increased or decreased. This may be accomplished by providing a PWM signal from a control system to a high power field effect transistor (FET) in series with the headlamp bulb. Another headlamp control example involves providing a PWM signal to a lamp driver integrated circuit such as a Motorola (Freescale Semiconductor) MC33286. This integrated circuit provides some added advantages such as limiting a maximum in-rush current to the headlamp, thus potentially extending the life of the headlamp bulb.
There is a continued need for further improvements in automotive lighting control.